UFC president Dana White today announced that Tito Ortiz has been forced out of the UFC Fight Night 24 main event, and Phil Davis has been tapped as a replacement opponent for Antonio Rogerio Nogueira.

MMAjunkie.com (www.mmajunkie.com) has learned from sources close to the promotion that an accidental training-session headbutt forced Ortiz to receive 22 stitches. An MRI and CT scan indicated no serious damage, but the wound was severe enough to force Ortiz to withdraw from the bout.

A timetable has not yet been determined for Ortiz's return – a bout White has referred to as a "must-win" matchup for the former light heavyweight champion.

UFC Fight Night 24 takes place March 26 at KeyArena in Seattle and airs live on Spike TV.

Davis (8-0 MMA, 4-0 UFC) had been expected to fight Matt Hamill at April's UFC 129 event, then Jason Brilz when Hamill was pulled in favor of a UFC 130 matchup with Quinton "Rampage" Jackson.

Davis, a former NCAA Division I national wrestling champion for Penn State, has made a smooth transition since his pro MMA debut in 2008. After signing with the UFC in early 2010, he extended his undefeated streak with decision wins over Brian Stann and Rodney Wallace and submission victories over Alexander Gustafsson and Tim Boetsch.

The recent win over Boetsch, which came via a modified hammerlock that Davis jokingly calls "the Mr. Wonderful" after his fighting nickname, earned him a "Submission of the Night" award.

Nogueira (19-4 MMA, 2-1 UFC), the twin brother of former UFC champ Antonio Rodrigo Nogueira, recent suffered a unanimous-decision loss to Ryan Bader in a key UFC 119 bout. Prior to the defeat, the PRIDE vet owned a seven-fight win streak, which included UFC wins over Luiz Cane (which earned a "KO of the Night" bonus) and Jason Brilz ("Fight of the Night").

For more on UFC Fight Night 24, stay tuned to the UFC Rumors section of MMAjunkie.com.